Question

Please help I was up till 2am trying to figure this out last night, Thanks
The top selling Red and Voss is rated 70,000 miles, which means nothing. In fact, the distance the tires can run until they wear out is a normally distributed random variable with a mean of 82,000 miles and a standard deviation of 6,400 miles.

a) What is the probability that the tire wears out before 70,000 miles?
b) What is the probability that the tire last more than 100,000miles?

Answer 1

Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions related to your Z scores.

Answer 2

Thank you PSyDAG